TALLAHASSEE, Florida (Reuters) - A Florida political activist filed a lawsuit on Monday seeking to force Gov. Rick Scott to appoint a new lieutenant governor, a post that has been vacant for nearly nine months.

Scott has been noncommittal about choosing a successor to Lt. Gov. Jennifer Carroll, who abruptly resigned in March after investigators questioned her about public relations work she did before taking office for a charity linked to an illegal gambling racket. Carroll was not charged with any wrongdoing.

Barbara DeVane, a retired social studies teacher who has long been active in education, labor and feminist causes, argued in the lawsuit that Scott is violating state law by not naming a new lieutenant governor.

DeVane cited a section of the state constitution which reads that when a vacancy occurs in the office, the governor "shall" appoint a successor.

"If the statute allowed the position to remain unfilled, it would provide 'the governor may appoint a successor,' but it does not," said DeVane's petition.

"There is no reasonable reading of the term that would allow the governor to shirk his duties for months on end, as he has here."

Last March, Scott said he would wait until after the legislative session ended in May to appoint a lieutenant governor.

The job has no official duties under state law, but Carroll and many of her predecessors served as a liaison to the business community as well as a political ally for the governor.

"The Governor is going to take the right time to find the right person," said Scott spokeswoman Melissa Sellers.

Florida's constitution does not provide a time limit for the governor to fill the vacancy, although he will have to choose a running mate for his already announced re-election campaign next summer.

Scott is widely expected to do so well before then.

"This is not a duty that the governor can choose to undertake when he feels like it," said DeVane's suit. It said the constitution provides for appointment "upon" a vacancy occurring, "and clearly does not mean several months later."